Method of and apparatus for drilling



M rch 1s 1924. 1,487,690

c. MARTl METHOD OF AND APPARATUS FOR DRILLING Filed Sept. 24, 1920'Patented Mar. 18, 1924.

iaaaeaa omrso STATES PATENT OFFICE.

CHARLES MARTI, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO THE MARTIAN'MANU- FACTURING ('10., INCL, OF NEWARK, NEW JERSEY, A CORPORATION OF NEWJERSEY.

METHOD OF AND APPARATUS FOR- DRILLING.

Application filed September 24, 1920. Serial No. 412,574.

To all whom it may concern.

Be it known that I, CHARLES MARTI, a citizen of the RepublicofSwitzerland, residing in East Orange, county of Essex, and

State of New Jersey, have invented an Improvement in Methods of andApparatus for Drilling, of which the following is a specification. v

The present invention relates to an im- 1 provement in method of andapparatus for drilling, one object being to prevent the breakage ofdrills particularly in so far as such breakage occurs substantiallycoincident with the passage of the drill throguh the farther oremergence surface of the article in which the drill is operated.

Mechanics have appreciated that the greater proportion of drillbreakage, particularly of small drills, occurs at this point in theoperation of drilling and they have adopted expedients for preventingit, such for example as reducing the rate of feed just as the drill isabout to penetrate the farther surface of the object being drilled. Itis true that this precaution on the part of an operator will save drillsto'some extent but at the same time, it requires practice to beeffective and also slows down the work of drilling to a considerableextent. It is therefore proposed to eliminate the skill and judgment ofthe operator by providing a method and suitable apparatus in connectionwith the use of which no judgment as to rate of speed need be exercisedexcept so far as is necessary in the ordinary operation of drillingwithout re ard to the passage of the drill through the farther surfaceof the article being drilled.

The application of my invention is illustrated in the drawingsaccompanying the present specification and in which Figure 1 is afragmentary view of a drill press in elevation parts of the improvedapparatus being broken away and parts be-- ing shown in section,

Figure 2, a view in transverse vertical section on the line 2-2 ofFigure 1,

Figure 3, a view in elevation of a modified form of apparatus forpracticing my improved method, i 7

Figure 4, a top plan view of the same, Figure 5, a view partly invertical section showing one embodiment of the invention applied as anintegral part of a drill press, and

Figure 6, a'view in elevation of the cap illustrated in Figure 5.

Referring to the drawings, a drill 1 of the ordinary type is operativelysecured to a chuck 2 which in turn is rotated by a spindle 3, saidspindle being also capable of longitudinal movement toward "and awayfrom the drill "press table 4, said movement being commonly efiected bymeans of a rack 5 cooperating with a pinion 6 mounted on a shaft 7, saidshaft being rotated by means of a lever 8 or other suitable handoperated member.

Referring more particularly to Figure 3 which illustrates a simpledevice for aiding the operation of my improved method, the drill 1 isshown as extending between the prongs 9 of a powerful spring 10 having abearing surface 11 for the chuck or other drill carrying member. In thepractice of my improved method, it is contemplated that the drill willbe advanced normally through the article to be drilled until it reachesa predetermined position therein, this position being approximatelywhere the drill point will pierce the remote'or far surface of thearticle. At this point, I interpose the yielding resistance to thefurther advance of the drill, said resistance being maintained until thecutting. edge of the drill has passed entirely through the remotesurface. This resistance may be produced by any suitable means but Ihave found that a steel spring is of great effectiveness for the desiredpurpose. Where a resistance member such as a spring 10 is used, theoperator will slide the prongs 9 into position astride of the drill atany time before the critical position is reached, the critical positionin this .connection meaning that point in the advance of the drill atwhich the foremost cutting edge is about to pierce the remote surface ofthe article. This type of spring may conveniently be used Where thearticles tobe drilled. are of uniform thickness and where each drillingoperation is practically a repetition of the former operation on thesame machine.

Where it is contemplatedthat the method is to be used in connection witha more varied character of Work, suitable apparatus may be embodied inthe drilling machine either as an attachment thereto or as an integralpart thereof. It is obvious that the principle of interposing theyielding resistance may be applied in a great variety of ways and bymeans of varying forms of mechanism. Referring now more particularly toFigures 1 and 2 which illustrate'an attachment to a standard form ofdrill press, it will be noted that this attachment comprises a springcompressing member 12, having a threaded portion 13 adapted to besecured to the shaft 7 of the drill press. This threaded portion 13 ispreferably a lefthanded thread so that the spring compressing member mayrotate. in'the direction of the rotation of the shaft 7 when the same isactuated by the operator and without becoming disengaged from said shaftduring said operation. A spring 14 may be secured so as to rotate withspring compressing member 12 by means of a pin 15 passing through oneleg of said spring and securing the same to said member 12. The springcompressing member is also provided with a projecting lug or pin 16adapted to engage one free end 17 of the spring 14 and press the sametoward the other end 18 of said spring, the position of said end18'being fixed by means of a projecting lug 19 secured to a cap orhousing 20 which may be made in two portions secured together by rivetsor other suitable means. This housing 20 is loosely mounted on a stud 21which may conveniently be formed integral with the spring compressingmember 12, said housing being retained against movement of rotation bymeans of a lever having one end 22 engaging peripheral projections 28 ofthe housing, while the other end 24 engages a rigid portion 25 of thedrill press head. The stud 21 which projects from each side of themember 12 is proportioned to support loosely the lever which slideslongitudinally with respect to said stud in order to engage anddisengage the projections 23 of the housing 20. This means for settingthe stationary position of the housing 20 and therefore of the springretaining or resisting pin 19 is provided to give a wider range ofadjustability so that the same device may be eifective in. connectionwith the drilling of articles of varying shapes and thicknesses.

In operating the attachment, the drill is first moved into aposition.corresponding substantially with that indicated in Figure l, inother words, so that the point of the drill will be resting upon theupper level of the drill press table or bed. The parts of the apparatus.will then be adjusted so that pin 19, secured to the housingwill occupya fixed position byreason' of theengagement,

of the lever against a rigid portion'of! the framework of. thfmachinearid the. .pin 16 w l e in easeme t erased 17 of the spring 14,the other free end of said spring being pressed against the nowstationary pin 19. By reyersing the direction of the feeding handle, thedrill will then be raised to permit the piece of work to be positionedon the drill press. The normal operation'of drilling and feeding thentakes place and'the operator need have no further concern respecting thedistance to feed the drill or with respect to the emergence of the drillthrough the article on the remote side. He simply continues feedingnormally until the feeding operation is completely pre. vented by reasonof the compression of spring 14 bringing the free end 1'? into contactwith the now stationary free end 18, thus permitting no further rotationof the shaft 7 through which the longitudinal advance of the drill isaccomplished.

Referring now to i igure 5, it will be clear that the present inventionmay be embodied directly in a drill press structure, thus per mittingthe elimination of the lever. In the device shown in Figure 5, a springcompressing member 26 may be associated in any suitable secure relationwith the drill feeding pinion of the drill press. said member 26 beingprovided with a stud 27 upon which is loosely mounted a cap 28 having aplurality of holes 29 adjacent to its periphery, said holes beingarranged to receive a pin or pins 30 mounted in the head of the drillpress. The cap 28 is also provided with aspring detaining pin 31 whichbecomes a stationary stop when the holes 29 engage the pins 30. The capis retained in operative position as described by means of a compressionspring 32 interposed between said cap and a head 33 secured to the outerend of the stud 27. Thus, when it is desired to change the position ofthe pin 31, the cap 28 is raised against resistance of the spring 32 androtated to the desired position. Similarly, if it is desired to throwthe drill protecting mechanism out of operation, the cap may be raisedout of engagement with the pins 30 thus withdrawing the stop pin 31 fromthe path of movement of the spring 14 and the cap may then be positionedwith portions of its undersurface resting against the tops of the pins30.

Whatever form of apparatus is used, it will be clear that theinterposing of a suitable yielding resistance to the advance of thedrill just before the drill is about to penetrate the far side of theobject drilled will prevent the sudden forward thrust of the drillthrough thethin metal. Thus, it may be said that the yielding resistanceinterposed' as described, is me. sense substituted for thenorm'alresistanceof the metal to theadvance of the drill during, the lastincrement of its passage through the article. Where theyieldingresistance is'in the form of a t i lie are l us ted a scribed orequivalent thereto, the drilling operation will be stopped automaticallyat the proper time so that, after a proper setting of the instrument hasbeen effected, the operator need give no attention to stopping thefeeding of the drill.

I claim as my invention:

1. In a drill press the combination of a longitudinally movabledrill'holder, a pinion operatively connected therewith, a housing tosupport said pinion, a lug secured eccentrically to said pinion androtatable therewith, a stop operatively secured to the housing, andmeans interposed between the lug and the stop to yieldingly opposerotation of the pinion.

2. In a drill press the combination of a longitudinally movable drillholder, a pinion operatively connected therewith, a housing to supportsaid pinion, a lug secured eccentrically to said pinion and rotatabletherewith, a stop operatively secured to the housing, means foradjusting the position of the stop, and means interposed between the lugand the stop to yieldingly oppose rotation of the pinion.

3. Apparatus for drilling comprising in combination a longitudinallymovable drill holder, a pinion operatively connected therewith, ahousing to support said pinion and means interposed between said housingand said pinion to yieldingly oppose drill advancing rotation of thepinion.

4. Apparatus for drilling comprising in combination a longitudinallymovable drill holder, a pinion operatively connected therewith, ahousing to support said pinion and means interposed between said housingand said pinion to yieldingly oppose drill advancing rotation of thepinion after a predetermined increment of unopposed rotation thereof.

5. Apparatus for drilling comprising in combination a longitudinallymovable drill holder, a pinion operatively connected therewith, ahousing to support said pinion, means interposed between sald housingand saidpinion to yieldingly oppose drill advancing rotation of thepinion, and means for positively stopping said drill advancing rotationof the pinion.

6. Apparatus for drilling comprising in combination a longitudinallymovable drill holder, a pinion operatively connected therewith, ahousing to support said pinion, means interposed between said housingand said pinion to yieldingly oppose drill advancing rotation of thepinion, and means for positively stopping said drill advancing rotationof the pinion after a predetermined increment of yieldingly opposedrotation thereof.

7. In a drill press the combination of a longitudinally movable'drillholder, a pinion operatively connected therewith, a housing to supportsaid pinion, a lug secured eccentrically to said pinion and rotatabletherewith, a stop operatively secured to the housing, and a U-shapedspring having one leg positioned to engage" the stop and the otherpositioned to engage the lug to yieldingly oppose movement of rotationof the pinion. 8. In a drill press-the combination of a drill presshead, a longitudinally movable drill holder, a pinion operativelyconnected therewith and supported by said head, a disc rotatable withthe pinion and having a lug, a housing having a stop member extendingtoward the disc, a spring positioned to engage both the lug and the stopmember, and

means to retain the housing against movement of rotation when the pinionis rotated in spring compressing direction.

9. An attachment for drill presses comprising a lever, a housing mountedon said lever, a spring positioned in the housing, means secured to thehousing to engage a portion of said spring to .limit movementthereof,and means movable within the housing to engage another portion of saidspring to move the same'toward the first mentioned portion. c

10. An attachment for drill presses comprising in combination a U-shapedspring member, a stop positioned to engage one end of said member tolimit movement thereof, means for moving the other end of the springmember toward the first mentioned end, and means for retaining the stopin fixed position with respect to a drill press to which the attachmentis secured.

11. An attachment for drill presses comprising a lever, a housingmounted on said lever, a spring in the housing, a stop fixed withrespect to the housing and positioned to engage one portion of thespring, and

spring engaging means movable within the housing to press anotherportion of the I spring toward the first mentioned portion. In testimonywhereof, I have signed my name to this specification this 17th day ofSeptember, 1920.

CHARLES MARTI.

